Consolidate documentation (#3071)

* 🔥 consolidate documentation
* ♻️ overwork std specializations
* 🚚 move images files to mkdocs
* ♻️ fix URLs
* 🔧 tweak MkDocs configuration
* 🔧 add namespaces
* 📝 document deprecations
* 📝 document documentation generation
* 🚸 improve search
* 🚸 add examples
* 🚧 start adding documentation for macros
* 📝 add note for https://github.com/nlohmann/json/issues/874#issuecomment-1001699139
* 📝 overwork example handling
* 📝 fix Markdown tables

doc/mkdocs/docs/api/basic_json/accept.md

@@ -1,4 +1,4 @@
-# basic_json::accept
+# <small>nlohmann::basic_json::</small>accept
 
 ```cpp
 // (1)
@@ -17,7 +17,7 @@ Checks whether the input is valid JSON.
 1. Reads from a compatible input.
 2. Reads from a pair of character iterators
     
-    The value_type of the iterator must be a integral type with size of 1, 2 or 4 bytes, which will be interpreted
+    The value_type of the iterator must be an integral type with size of 1, 2 or 4 bytes, which will be interpreted
     respectively as UTF-8, UTF-16 and UTF-32.
     
 Unlike the [`parse`](parse.md) function, this function neither throws an exception in case of invalid JSON input
@@ -84,7 +84,21 @@ Linear in the length of the input. The parser is a predictive LL(1) parser.
     --8<-- "examples/accept__string.output"
     ```
 
+## See also
+
+- [parse](parse.md) - deserialize from a compatible input
+- [operator>>](operator_gtgt.md) - deserialize from stream
+
 ## Version history
 
 - Added in version 3.0.0.
 - Ignoring comments via `ignore_comments` added in version 3.9.0.
+
+!!! warning "Deprecation"
+
+    Overload (2) replaces calls to `accept` with a pair of iterators as their first parameter which has been
+    deprecated in version 3.8.0. This overload will be removed in version 4.0.0. Please replace all calls like
+    `#!cpp accept({ptr, ptr+len}, ...);` with `#!cpp accept(ptr, ptr+len, ...);`.
+
+    You should be warned by your compiler with a `-Wdeprecated-declarations` warning if you are using a deprecated
+    function.